WASHINGTON (AP) -- The government is scrambling to find the source of a salmonella outbreak likely linked to ground turkey that has killed one and sickened dozens more.

Finding the source of an outbreak hasn't been easy; the government has been chasing the illnesses for months. The Agriculture Department, which oversees meat safety, said it is still investigating who produced the meat, and the department hasn't initiated a recall.

California state health officials said Tuesday that the one death was in Sacramento County. Seventy-six people in 26 states have been made sick from the same strain of the disease.

The illnesses date back to March, and the federal Centers for Disease Control and Prevention said Monday that cultures of ground turkey from four retail locations between March 7 and June 27 showed contamination with the same strain of salmonella, though those samples were not specifically linked to the illnesses. The agency said preliminary information showed that three of those samples have been linked to the same production establishment but it did not name the retailers or the manufacturers.

The silence from government officials may be attributed to USDA rules that make it harder to investigate and recall salmonella-tainted poultry. Because salmonella is common in poultry, it is not illegal for meat to be tainted with the pathogen. Officials must directly link the salmonella illnesses with a certain producer or establishment, which is difficult to do because people don't always remember what they ate or where they bought it.

In this case, it appears that officials haven't been able to prove the link between the samples of salmonella they found -- even though they are the same strain -- and the 77 people who were sickened. USDA's Food Safety and Inspection Service sent out an alert about the illnesses late last week telling consumers to properly cook their turkey, which can decrease the chances of salmonella poisoning. But the department has not given consumers any further warnings about the source of the tainted meat.

"Despite an extensive investigation by FSIS and CDC to date, there is little epidemiological information available at this time that conclusively links these illnesses to any specific product or establishment," FSIS spokesman Neil Gaffney said Tuesday. "Without specific enough data, it would not be appropriate to issue a recall notice." Gaffney said the agency was committed to finding the source of the outbreak and then take action to protect public health.

Art Caplan, a bioethicist at the University of Pennsylvania, said the government's handling of the outbreak raises ethical questions about why the public wasn't warned sooner.

"You've got to protect the public health. That's their first and primary value -- not industry, not any other goal. They have to warn as quickly as they think there's reasonable evidence for concern," Caplan said.

He said uncertainty about the outbreak's source might explain the long silence, but he added, "The moral duty is to really get the word out as soon as you have evidence of a problem."

The illnesses are spread all over the country. The states with the highest number sickened were Michigan and Ohio, 10 illnesses each, while nine illnesses were reported in Texas. Illinois had seven, California six and Pennsylvania five.

The remaining states have between one and three reported illnesses linked to the outbreak, according to the CDC: Alabama, Arizona, Georgia, Iowa, Indiana, Kentucky, Louisiana, Massachusetts, Minnesota, Missouri, Mississippi, North Carolina, Nebraska, Nevada, New York, Oklahoma, Oregon, South Dakota, Tennessee and Wisconsin.

A chart on the CDC's website shows cases have occurred every month since early March, with spikes in May and early June. The latest reported cases were in mid-July, although the CDC said some recent cases may not have been reported yet.

CDC spokeswoman Lola Russell said Tuesday it can take three to four weeks to confirm a single case. Identifying an outbreak can take considerably longer than that when cases of foodborne illness occur sporadically, in several states, as has happened in the current outbreak, she said.

Dr. Mark Dworkin, a public health expert at the University of Illinois at Chicago, said it's not surprising that the government alert came months after the first cases were identified.

Outbreaks of foodborne illnesses where "everybody came together at a church supper and ate the same food" are easier to identify than those involving people in many states, he said. "The problem we have is our food is contaminated too often. It's not acceptable that such a large percentage of ground turkey has got such a potentially deadly pathogen."

Ground turkey is considered safe to eat when the internal temperature reaches 165 degrees during cooking. For turkey patties or burgers, internal temperatures on each side should be measured. The government also advises refrigerating meat promptly and washing hands for at least 20 seconds before and after handling raw meat or poultry.

The CDC estimates that 50 million Americans each year get sick from food poisoning, including about 3,000 who die.

Salmonella causes most of these cases and federal health officials say they've made virtually no progress against it.

The most common symptoms of salmonella are diarrhea, abdominal cramps and fever within eight hours to 72 hours of eating a contaminated product. It can be life-threatening to some with weakened immune systems.
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Tanner reported from Chicago. Associated Press writer Shaya Tayefe Mohajer in Los Angeles contributed to this report.